Message2851

While we're looking at it, there's a related thing we're not currently handling
properly, and that's if the initial state should be pruned because of its
heuristic value.
Currently, we add it to the open list unconditionally, and this happens to work
by accident, but the output is messed up (e.g. showing that a state with a
heuristic value of 2147483647 is expanded). This also causes an
out-of-memory-style error when using single_buckets() since the code attempts to
create 2147483648 buckets. For example, try
$ ./plan ../benchmarks/mystery/prob07.pddl --search 'eager(single_buckets(blind()))'
The better solution would be to use the same criteria (and ideally the same
code, factored out) as during state expansion for deciding whether the initial
state should be added to the open list.